How to: Joints follow Mesh vertex

It looks like a good way by using emitter and parentConstraint for the facial rig.
But, if emitter as the parent obj will be easy crash maya when do undo. So it will more stablelize adding locator as child.
I need do more test.
emitter+parentCons看來是不錯的方法
但是，如果直接用emitter當做父物件，如果undo似乎很容易照成Maya當機
多加上locator跟emitter連結，當調劑似乎又比較好一些
還要再多測試

Recently I've been tyring use point on poly constraint for facial rig. The result also quite good.
But when the mesh be changed the vertex position, the following obj which using point on poly constraint will not only change the translation but rotation, so need to add one more child obj to avoid this kind situation.
And one more thing, the face mesh for using point on poly needs to be triangular.

create followingNode(group) for each vertex point on FaceDrMesh and using Point On Poly constraint connecting them.
create frzNode(group) and hookNode( joint ) as a set for each followingNode and using point constraint connecting them.